Phylogeny of the portulacaceous cohort based on ndhF sequence data

The Portulacaceae, Basellaceae, Cactaceae, and Didiereaceae form a monophyl etic group within the Caryophyllales, and evidence exists that the first ma y be paraphyletic ii the latter three are recognized at the familial level. Several taxonomic treatments of the Portulacaceae based on morphological f eatures have failed to produce consensus regarding infrafamilial relationsh ips. The present paper employs sequences of the chloroplast gene ndhF to pr oduce a molecular phylogeny of the portulacaceous cohort, focusing on the r elationship among major lineages of the Portulacaceae and the three familie s potentially derived from within them. Results of this analysis supported two major clades within the monophyletic cohort. The first included Portula ca, Anacampseros and its relatives, mud, of Talinum, Talinella, and Cactace ae; the second, weakly supported, included the remaining genera of Portulac aceae, Basellaceae, and Didiereaceae. This phylogeny also showed that sever al generic circumscriptions remain inadequate, particularly that of Talinum sensu late, which was polyphyletic in this analysis, and that all present classifications of the Portulacaceae include demonstrably non-monophyletic tribes.